Ditch Your Fixed Rate Calculator
If rates have dropped noticeably since you fixed your mortgage, breaking the fix early to remortgage onto a new deal can genuinely save money — but only once the early repayment charge for leaving, and the fee for the new deal, are properly weighed against what the lower rate would actually save. This calculator runs that exact comparison using your own numbers, rather than a general rule of thumb, and gives a clear verdict on whether switching now is likely worth it.
Ditch Your Fix
Should you pay the Early Repayment Charge to leave your current fix early and switch to a better rate?
The Three Numbers That Actually Decide This
Three figures drive the entire decision: the early repayment charge for leaving your current fix, usually a percentage of your remaining balance; any product fee on the new deal; and the monthly saving the new, lower rate would actually produce. Add the first two together for your total exit cost, then divide that by the monthly saving to get a break-even point — how many months it takes the saving to cover what leaving actually costs. This calculator does exactly that calculation, but the useful part is what it does next: comparing that break-even point against how much time is actually left on your current deal.
It is worth having all three figures confirmed precisely, rather than estimated, before treating any result as final — your current lender can confirm the exact ERC that would apply, and a new lender or broker can confirm the exact fee and rate on offer, since even a small difference in any of the three inputs can shift the verdict meaningfully.
Why Break-Even Alone Isn’t the Whole Answer
A break-even point on its own does not tell the full story — what matters is whether that break-even happens before your current fix would have ended anyway. If the exit costs are recouped well before your existing deal’s natural end date, switching now is straightforwardly worth it, since you are locking in savings for months or years you would otherwise have paid the higher rate for. If the break-even point falls close to or after your current deal was going to end regardless, the case for paying to leave early weakens considerably, since you could simply wait and remortgage penalty-free at the natural end point instead.
This is the single most common mistake in evaluating whether to break a fix: looking only at the monthly saving and how long it takes to recoup the exit cost, without checking that timeframe against how much of the current deal is actually left. A saving that breaks even in eight months looks attractive on its own, but is much less compelling if only six months remain on the current fix anyway.
When Rates Have Moved Enough to Matter
A small rate difference is rarely worth an early repayment charge on its own — the exit cost needs a meaningful ongoing saving to justify it, and a marginal rate improvement can take so long to break even that it is not worth the disruption or cost of switching early. A larger rate drop changes the calculation considerably, since the monthly saving grows while the exit cost stays fixed, shrinking the break-even period. There is no single rate gap that always makes switching worthwhile — it depends on your specific balance, remaining term and exit costs, which is exactly why running your own numbers through this calculator matters more than a rule of thumb.
Same Rate Gap, Different Time Left
A £200,000 balance with 18 months left on a fix at 5.5%, facing a 2% ERC (£4,000) plus a £999 fee to switch to a new rate of 4.2%, might see a monthly saving in the low hundreds of pounds — producing a break-even point of perhaps 10 to 12 months, comfortably before the 18 months remaining on the current deal. That combination points toward a clear “worth switching” verdict. Change the remaining term to just 6 months instead, and the same break-even point now falls after the current deal would have ended anyway, tipping the same rate improvement toward “probably not worth it” — identical rates, a completely different conclusion, purely because of how much time was left.
The Verdict Isn’t Always Black or White
This calculator gives one of three outcomes: a clear “worth switching” when the exit costs are recouped comfortably before your current deal ends, a “probably not worth it” when break-even takes too long relative to your remaining term, and a genuine borderline case in between, where the decision comes down to how confident you are that a broadly similar or better rate will still be available when your current fix naturally ends. That middle case is common, and reasonable people can weigh it differently — there is no universally correct answer once the numbers are this close. Our Compare Fixed Rate Mortgages calculator is useful if you have not yet decided which new fixed term to move to, and our Compare Two Mortgages tool lets you compare two specific deals side by side once you have narrowed down the options.
Frequently Asked Questions
Can I switch to a new deal with my current lender without paying an ERC?
Some lenders allow a product transfer to a new rate without an early repayment charge, though this is generally only available once you are within a set window before your current fix ends, not at any point during the term.
Does the early repayment charge reduce over time?
Often yes — many fixed mortgages have a tiered ERC that reduces each year of the fix, meaning leaving in year four of a five-year fix typically costs less in ERC than leaving in year one would.
Is it worth switching just to release equity?
This is a different question from simply chasing a lower rate, since it depends on why the equity is needed and what alternative borrowing might cost instead. It is worth including any equity release goal explicitly in the comparison rather than treating it as a side benefit.
What if rates fall further after I switch?
This is a genuine risk with any decision to fix a rate — locking in today’s rate protects against rates rising, but if they fall further afterward, a new fix taken today will not benefit from that later drop until it too ends.
Does my credit score affect whether I can switch early?
Yes — a new fixed deal, whether with your current lender or a new one, is subject to its own affordability and credit assessment, so a change in your circumstances since you first fixed could affect what is available now.
How far in advance can I usually lock in a new rate?
Many lenders allow a new rate to be reserved three to six months ahead of when it actually starts, which is often used to line up a new deal to begin exactly when a current fix ends, avoiding both an early repayment charge and any gap on a standard variable rate.
Important Information
This calculator provides an estimate based on the figures and assumptions you enter and does not constitute financial advice. It does not predict future interest rates or guarantee any specific new deal will be available. For advice specific to your circumstances, consult a mortgage broker or FCA-regulated adviser. See our Disclaimer for further information.